An organic light emitting device (OLED) is typically formed of two electrodes (an anode and a cathode), with one or more organic material layers placed between these electrodes. In the organic light emitting device having such a structure, when a voltage is applied between the two electrodes, holes from the anode and electrons from the cathode flow into the organic material layer. The holes and the electrons are recombined to form excitons, and the excitons fall back to the ground state and emit photons that correspond to the energy difference. By this principle, the organic light emitting device generates visible light.
Recently, as the range of application of organic light emitting devices has broadened, studies on materials capable of improving the performance of organic light emitting devices have been actively conducted.